Liquid crystal display apparatus

ABSTRACT

A liquid crystal display apparatus includes a substrate and a second substrate with a liquid crystal layer sandwiched therebetween. A plurality of pixels are sandwiched between the two substrates and form a display section, each of the pixels is provided with first and second pixel electrodes both corresponding to the pixel, and a common electrode corresponding to the first and second pixel electrodes.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.09/938,619, filed Aug. 27, 2001, now U.S. Pat. No. 6,859,194, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid crystal display apparatushaving a new configuration.

Conventional liquid crystal display apparatuses employ a display moderepresented by a Twisted Nematic (TN) display mode and in which electricfields are applied substantially perpendicularly to a substrate surface(these electric fields are hereinafter referred to as “verticalfields”). The TN display mode, however, has the disadvantage of using asmall angle of visibility.

On the other hand, an In-Plane Switching (IPS) display mode has beenproposed in JP-B-63-21907, U.S. Pat. No. 4,345,249, WO No. 91/10,936,and JP-A-6-160878 and etc. specifications.

In this IPS display mode, an electrode for driving liquid crystals isformed on one of a pair of substrates that sandwiches the liquidcrystals therebetween, and electric fields substantially parallel with asurface of the substrate (these electric fields are hereinafter referredto as “horizontal fields”) are applied to the liquid crystals. Thisdisplay mode provides a larger angle of visibility than the TN displaymode.

FIG. 2 is a schematic sectional view showing an example of aconfiguration of a pixel portion of a liquid crystal display apparatususing the IPS display mode. The liquid crystal display apparatus has asubstrate 1, a substrate 2 arranged opposite the substrate 1, a liquidcrystal layer 12 sandwiched between the substrates 1 and 2, commonelectrodes 3 and pixel electrodes 4 for applying horizontal fields,insulated films 6 a and 6 b disposed on the substrate 1, aliquid-crystal orientation control layer 7 (hereinafter referred to asan “orientation film”) disposed on the insulated film 6 b, a colorfilter 8 and an orientation film 7 disposed on the substrate 2, andpolarizing plates 11 disposed on surfaces of the substrates 1 and 2which do not face the liquid crystals, the polarizing plates havingtheir own optical characteristics varied according to an orientationstate of the liquid crystals. The common electrodes 3 and 4 are linearand are arranged substantially in parallel.

In the IPS display mode, the common electrodes 3 and the pixelelectrodes 4 generate horizontal fields as shown by equipotential linesin FIG. 2. Images are displayed when these fields cause the liquidcrystals to rotate within a plane substantially parallel with thesubstrate 1.

SUMMARY OF THE INVENTION

There are now needs for a display monitor that can reliably reproducecolors, but the above described IPS display mode is disadvantageous inthat color tones vary depending on a driving voltage.

Means for solving this problem has been reported in JP-A-9-297299specification. The means reported in this publication, however, solvesthe problem with a combination of a light source and a liquid crystalpanel. Thus, to widen a range of light sources any of which are to beselected, a means is desirable which restrains a variation in colortones using only the liquid crystal panel.

Further, the means reported in JP-A-9-297299 specification desirablysets a retardation d_(eff)·Δn_(eff) at a small value of 250 nm or less(where d_(eff) denotes an effective thickness of the liquid crystallayer and Δn_(eff) denotes an effective refractive-index anisotropy ofthe liquid crystals). This setting requires a gap and therefractive-index anisotropy to be reduced. A reduction in the gap maylower productivity, while a reduction in refractive-index anisotropynarrows the range of liquid crystals any of which are to be selected.Thus, solving these problems requires a means that does notsubstantially restrict the retardation.

It is an object of the present invention to provide a liquid crystaldisplay apparatus having a new configuration and which restrains avariation in color tones on a display panel depending on a drivingvoltage without any unreasonable restrictions on retardation, using onlythe liquid crystal panel.

The present invention, adapted to attain the above object, will bedescribed below in brief.

-   -   [1] A liquid crystal display apparatus having a first substrate,        a second substrate arranged opposite the first substrate, a        liquid crystal layer sandwiched between the first substrate and        the second substrate, and a plurality of pixels forming a        display section,        -   in which each of the pixels is provided with a first pixel            electrode and a second pixel electrode both corresponding to            the pixel, and a common electrode corresponding to the first            and second pixel electrodes.    -   [2] A liquid crystal display apparatus having a first substrate,        a second substrate arranged opposite the first substrate, a        liquid crystal layer sandwiched between the first substrate and        the second substrate, and a plurality of pixels forming a        display section,        -   in which each of the pixels has a first and a second pixel            electrodes each corresponding to the pixel and disposed on            the first substrate, and a common electrode corresponding to            the first and second pixel elements and disposed on the            first substrate.

The first and second pixel electrodes can desirably provide each of thepixels with a corresponding potential.

The apparatus desirably includes a first signal driver for supplying apotential to the first pixel electrodes, a second signal driver forsupplying a potential to the second pixel electrodes, and a signalcontrol circuit for controlling signals transmitted to the first andsecond signal drivers.

-   -   [3] A liquid crystal display apparatus in which the first pixel        electrodes, the common electrodes, and the second pixel        electrodes are disposed on the first substrate.

In each pixel, the first pixel electrode and the common electrode may belinear and may be arranged substantially in parallel, and the secondpixel electrode may be located between the first pixel electrode and thecommon electrode.

In this case, when a difference between the potentials provided to thefirst pixel electrode and to the common electrode is largest orsmallest, the potential provided to the second pixel electrode isdesirably substantially equal to an average of the potentials providedto the first pixel electrode and to the common electrode.

Furthermore, desirably, plural pieces of the first pixel electrodearranged in each pixel are connected together via a first junction,plural pieces of the second pixel electrode arranged in each pixel areconnected together via a second junction, the plural pieces of the firstpixel electrode and the first junction do not overlap the plural piecesof the second pixel electrode and the second junction, the first pixelelectrode, the second pixel electrode, the first signal line, and thesecond signal line are arranged in the same layer, and the commonelectrode and scan line are arranged in the same layer.

Further, at least part of the second pixel electrode may overlap thefirst pixel electrode or the common electrode, the second pixelelectrode may be linear, the second pixel electrode may be as wide as ornarrower than the first pixel electrode or common electrode, which isoverlapped by the part of the second pixel electrodes, the second pixelelectrode may be linear, and the second pixel electrode may be widerthan the first pixel electrode or common electrode, which is overlappedby the part of the second pixel electrode.

In this case, when the difference between the potentials provided to thefirst pixel electrode and to the common electrode is largest orsmallest, the potential provided to the second pixel electrode desirablysubstantially equals the potential provided to either the first pixelelectrode or the common electrode.

Furthermore, desirably, the plural pieces of the first pixel electrodearranged in each pixel are connected together via a first junction, theplural pieces of the second pixel electrode arranged in each pixel areconnected together via a second junction, the plural pieces of the firstpixel electrode and the first junction do not overlap the plural piecesof the second pixel electrode and the second junction, the first pixelelectrode, the second pixel electrode, the first signal line, and thesecond signal line are arranged in the same layer, and the commonelectrode and scan line are arranged in the same layer.

Further, the first pixel electrode and the common electrode may belinear and may be arranged substantially in parallel, the second pixelelectrode may be located below the first pixel electrode and the commonelectrode, the second pixel electrode overlaps the first pixel electrodeand the common electrode, and insulated films may be disposed betweenthe second pixel electrode and the first pixel electrode and between thesecond pixel electrode and the common electrode.

In this case, when the difference between the potentials provided to thefirst pixel electrode and to the common electrode is largest orsmallest, the potential provided to the second pixel electrode isdesirably substantially equal to the average of the potentials providedto the first pixel electrode and to the common electrode.

Further, the first and second pixel electrodes may be linear and may bearranged substantially in parallel, the common electrode may be locatedbetween the first pixel electrode and the second pixel electrode, atleast part of the common electrode may overlap the first pixel electrodeor the second pixel electrode, the first and second pixel electrodes maybe linear and may be arranged substantially in parallel, the commonelectrode may be located below the first and second pixel electrodes,the common electrode overlaps the first and second pixel electrodes, andinsulated films may be disposed between the common electrode and thefirst pixel electrode and between the common electrode and the secondpixel electrode.

In this case, when the difference between potentials provided to thefirst pixel electrode and to the common electrode is largest orsmallest, the potential provided to the second pixel electrode desirablysubstantially equals the potential provided to the first pixelelectrode.

Furthermore, desirably, the plural pieces of the first pixel electrodearranged in each pixel are connected together via a first junction, theplural pieces of the second pixel electrode arranged in each pixel areconnected together via a second junction, the plural pieces of the firstpixel electrode and the first junction do not overlap the plural piecesof the second pixel electrode and the second junction, the first pixelelectrode, the second pixel electrode, the first signal line, and thesecond signal line are arranged in the same layer, and the commonelectrode and scan line are arranged in the same layer.

-   -   [4] A liquid crystal display apparatus in which the first and        second pixel electrodes are disposed on the first substrate, and        the common electrodes are disposed on the second substrate.

Desirably, in each pixel, the first and second pixel electrodes may belinear and may be arranged substantially in parallel, and the commonelectrode overlaps the first and second pixel electrodes.

Further, a dielectric of 1.5 μm thickness may be arranged on the commonelectrode, and a portion of the dielectric which overlaps the commonelectrode includes a recess penetrating the dielectric or having a depthamounting to 50% or more of the thickness.

In this case, when the difference between the potentials provided to thefirst pixel electrode and to the common electrode is largest orsmallest, the potential provided to the common electrode is desirablysubstantially equal to the average of the potentials provided to thefirst pixel electrode and to the second pixel electrode.

-   -   [5] Desirably, the liquid crystal apparatus includes a scan        driver, a plurality of first scan lines connected to the scan        driver, a plurality of first signal lines connected to the first        signal driver and disposed so as to cross the plurality of first        scan lines, and second signal lines connected to the second        signal driver, the plurality of pixels each correspond to an        area enclosed by a corresponding one of the plurality of first        scan lines and a corresponding one of the plurality of first        signal lines, the first pixel electrodes correspond to the first        signal lines, and the second pixel electrodes corresponds to the        second signal lines.

Desirably, the first substrate is provided with the first scan lines,the first signal lines, and first switch elements each arranged in aneighborhood of an intersection between the corresponding first scanline and first signal line, and the second substrate is provided withsecond scan lines connected to the scan driver and arranged so as tocross the second signal lines, the second signal lines, and secondswitch elements each arranged in a neighborhood of an intersectionbetween the corresponding second scan line and second signal line.

Alternatively, the first substrate is provided with the first scanlines, the first signal lines, the second signal lines, first switchelements each arranged in a neighborhood of an intersection between thecorresponding first scan line and first signal line, and second switchelements each arranged in a neighborhood of an intersection between thecorresponding first scan lines and second signal line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a sectional configuration of a pixel accordingto Embodiment 1 of a liquid crystal display apparatus of the presentinvention;

FIG. 2 is a view showing a sectional configuration of a pixel accordingto a conventional liquid crystal display apparatus;

FIGS. 3A and 3B are views showing a configuration of the pixel accordingto Embodiment 1 of the liquid crystal display apparatus of the presentinvention;

FIG. 4 is a diagram showing a configuration of Embodiment 1 of theliquid crystal display apparatus of the present invention;

FIGS. 5A and 5B are views useful in explaining control of a distributionof electric fields in the pixel portion according to Embodiment 1 of theliquid crystal display apparatus of the present invention;

FIG. 6 is a chart showing a dependence of color tones on a drivingvoltage according to Embodiment 1 of the liquid crystal displayapparatus of the present invention;

FIGS. 7A and 7B are views showing a configuration of the pixel accordingto the conventional liquid crystal display apparatus;

FIG. 8 is a diagram showing a configuration of the conventional liquidcrystal display apparatus;

FIG. 9 is a chart showing a dependence of color tones on a drivingvoltage according to the conventional liquid crystal display apparatus;

FIG. 10 is a view showing a sectional configuration of a pixel accordingto Embodiment 3 of the liquid crystal display apparatus of the presentinvention;

FIG. 11 is a view showing a sectional configuration of a pixel accordingto Embodiment 4 of the liquid crystal display apparatus of the presentinvention;

FIG. 12 is a view showing a sectional configuration of a pixel accordingto Embodiment 5 of the liquid crystal display apparatus of the presentinvention;

FIGS. 13A and 13B are views showing a sectional configuration of a pixelaccording to Embodiment 6 of the liquid crystal display apparatus of thepresent invention;

FIGS. 14A and 14B are views showing a sectional configuration of a pixelaccording to Embodiment 7 of the liquid crystal display apparatus of thepresent invention;

FIGS. 15A and 15B are views showing a sectional configuration of a pixelaccording to Embodiment 8 of the liquid crystal display apparatus of thepresent invention;

FIGS. 16A and 16B are views useful in explaining control of thedistribution of electric fields in the pixel portion according toEmbodiment 8 of the liquid crystal display apparatus of the presentinvention;

FIGS. 17A and 17B are views showing a sectional configuration of a pixelaccording to Embodiment 9 of the liquid crystal display apparatus of thepresent invention;

FIGS. 18A and 18B are views showing a sectional configuration of a pixelaccording to Embodiment 10 of the liquid crystal display apparatus ofthe present invention;

FIGS. 19A and 19B are views showing a sectional configuration of a pixelaccording to Embodiment 11 of the liquid crystal display apparatus ofthe present invention;

FIG. 20 is a view showing a sectional configuration of a pixel accordingto Embodiment 12 of the liquid crystal display apparatus of the presentinvention;

FIG. 21 is a view showing a sectional configuration of a pixel accordingto Embodiment 13 of the liquid crystal display apparatus of the presentinvention; and

FIG. 22 is a view showing a sectional configuration of a pixel accordingto Embodiment 14 of the liquid crystal display apparatus of the presentinvention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The causes of the variation in the color tones in the IPS display modewill be described below.

The transmissivity (T) in the IPS display mode is expressed by Equation[1]:T=T ₀·sin²(2φ)·sin²((π·d _(eff) ·Δn _(eff))/λ  [1]where T₀ denotes a correction factor, φ denotes the angle between aneffective optical axis of a liquid crystal and a polarization directionof incident light, and λ denotes the wavelength of the incident light.

Accordingly, when the angle between the effective orientation directionof the liquid crystal and the polarization direction of the incidentlight is π/4 radian (45°), light of the wavelength λ, which is doublethe effective retardation d_(eff)·Δn_(eff), exhibits the highesttransmissivity. That is, the variation in the effective retardationd_(eff)·Δn_(eff) varies the wavelength having the highesttransmissivity, thereby varying the color tones.

Thus, the reason why the color tones, which have been bluish, becomeyellowish as the driving voltage increases is shown below. With a lowdriving voltage, the effective thickness d_(eff) is small due to themovement of part of the liquid crystal layer. With a high drivingvoltage, the effective thickness d_(eff) is large due to the movement ofthe entire liquid crystal layer.

The problems with the variations in color tones can be solved asdescribed below.

Equation [1] indicates that the wavelength λ having the highesttransmissivity is double the wavelength of the effective retardationd_(eff)·Δn_(eff). Accordingly, by adjusting the Δn_(eff) so as to offsetthe variation in the effective thickness d_(eff) depending on thedriving voltage, the variation in effective retardation d_(eff)·Δn_(eff)as well as the variation in the wavelength λ having the highesttransmissivity can be restrained.

The effective refractive-index anisotropy Δn_(eff) can be adjusted inthe following manner: When all the liquid crystals rise at a risingangle φ from the substrate 1, the effective refractive-index anisotropyΔn_(eff)=cosθ·Δn, where Δn denotes the refractive-index anisotropy ofthe liquid crystal. Accordingly, the effective refractive-indexanisotropy Δn_(eff) can be adjusted by regulating the start-up of theliquid crystals. In the above described conventional IPS display mode,since the liquid crystals are moved by the horizontal fields, the liquidcrystals will not rise, and the refractive-index anisotropy Δn_(eff) ofthe liquid crystals substantially equals the refractive-index anisotropyΔn thereof. When, however, electric fields having vertical fieldcomponents are applied to the liquid crystals, the latter, having apositive dielectric anisotropy, rise to reduce the effectiverefractive-index anisotropy Δn_(eff) of the liquid crystals.

When the liquid crystals rise to reduce the effective refractive-indexanisotropy Δn_(eff), the transmissivity of blue light, having a shortwavelength, increases as shown by Equation [1].

In the conventional IPS display mode, the color tones become yellowishas the driving voltage increase. This problem can be solved by thepresent invention in the following manner: With a low driving voltage,no vertical field components are applied, thus preventing the liquidcrystals from rising. At this time, a backlight or the gap is regulatedso as to obtain a desired white. With a high driving voltage, verticalfield components are applied to raise the liquid crystals, therebyreducing the effective refractive-index anisotropy Δn_(eff). At thistime, the blue, having a short wavelength, is emphasized to prevent thecolor tones from becoming yellowish. In this manner, the variation inthe color tones depending on the driving voltage can be restrained.

As described above, if the color tones become yellowish as the drivingvoltage increases, the liquid crystals may be prevented from rising whenthe driving voltage is lowest, and may be raised when it is highest. Oncontrary, if the color tones become bluish as the driving voltageincreases, the liquid crystals may be raised when the driving voltage islowest, and may be prevented from rising when it is highest. On theother hand, if, instead of varying monotonously, the color tones becomebluish and yellowish as the driving voltage varies, the liquid crystalsmay be prevented from rising when the color tones become bluest, and maybe raised when they become yellowest.

According to the present invention, the liquid crystal panel alone canrestrain the variation in the color tones depending on the drivingvoltage, with no particular restrictions on the light source. Further,the variation in the color tones depending on the driving voltage can berestrained without any restrictions on the retardation. Consequently,the refractive index or anisotropy of the liquid crystals is notrestricted, and those crystals are available which have a highrefractive-index anisotropy but are quick to respond and which have awide range of operative temperatures.

It has been reported that when the face color of people in an imagebecome bluish, viewers get the impression that the image is moredegraded (Video Information Media Society Magazine, Vol. 54, No. 1, p.93 to 100 (2,000)). Thus, in an animated image with a large number ofpeople displayed, the face color can be restrained from becoming bluishby restraining the liquid crystals from rising, while making the displayyellowish. That is, natural animated images can be displayed. On thecontrary, for a display for a word processor program or the like, imagescan be clearly displayed by raising the liquid crystals and making thedisplay bluish.

Equation [1] represents a transmissivity obtained in a normally blackmode in which the apparatus enters a dark state when the driving voltageis low. The present invention, however, restrains the variation in thecolor tones by adjusting the retardation, and is thus applicable even toa normally white mode in which the apparatus enters a bright state whenthe driving voltage is low.

JP-A-9-244046 specification reports means for forming vertical fieldcomponents to modulate the color tones. The means reported in this formsvertical field components on the basis of the difference between theaverage potential pair of comb teeth electrodes disposed on one of thesubstrates, and the potential at an opposite electrode disposed on theother substrate substantially halfway between the comb teeth electrode.In a manufacturing process, however, the upper and lower substrates maybe misaligned, and the resulting locational relationship between thepair of comb teeth electrodes and the opposite electrode may not be asdesigned. In this case, the distribution of electric fields applied tothe liquid crystals significantly differs from the design. Thus, toobtain desired chromaticity and brightness, the relationship between thepotential at the comb teeth electrodes and the potential at the oppositeelectrode must be adjusted for each liquid crystal display apparatus.

The present invention is adapted to solve the above problems, and it isan object thereof to provide a configuration that prevents thedistribution of electric fields applied to the liquid crystals even ifthe upper and lower substrates are misaligned as well as a new methodfor controlling vertical and horizontal field components.

Next, the present invention will be more specifically described on thebasis of embodiments.

[Embodiment 1]

The configuration of Embodiment 1 of the present invention will bedescribed with reference to FIGS. 3A, 3B, and 4. FIGS. 3A and 3B areviews useful in explaining the configuration of a pixel portion, andFIG. 4 is a view useful in explaining a driving system for a liquidcrystal display apparatus. More specifically, FIG. 3B is a bird's eyeview useful in explaining the configuration of a pixel 41 on a substrate1, FIG. 3A is a sectional view taken along line A-A′ in FIG. 3B, andFIG. 4 is a view useful in explaining a configuration for wiring on thesubstrate 1.

A liquid crystal display apparatus of this embodiment has aconfiguration described below.

As shown in FIGS. 3A and 3B, the apparatus has a substrate 1, asubstrate 2, a liquid crystal layer 12 sandwiched between the substrates1 and 2 and having a positive dielectric anisotropy, a plurality ofpixels 41 forming a display section, a first pixel electrode 4 and asecond pixel electrode 5 corresponding to the pixel 41, and a commonelectrode 3 corresponding to the first pixel electrode 4 and the secondpixel electrode 5.

Further, as shown in FIG. 4, the apparatus comprises a first signaldriver 32 for supplying a potential to the first pixel electrodes 4, asecond signal driver 33 for supplying a potential to the second pixelelectrodes 5, a signal control circuit 36 for controlling signalstransmitted to the first signal driver 32 and the second signal driver33, a common electrode driver 34 for supplying a potential to the commonelectrode 3, a scan driver 31 for selecting pixels, a signal controlcircuit 36, and a display control circuit 37 for controlling the firstand second signal drivers 32 and 33, the common electrode driver 34, andthe scan driver 31. The substrate 1 comprises a plurality of scan lines21 connected to the scan driver 31, a plurality of first signal lines 22a connected to the first signal driver 32, crossing the scan lines 21,and corresponding to the first pixel electrodes 4, a plurality of secondsignal lines 22 b connected to the second signal driver 33, crossing thescan lines 21, and corresponding to the second pixel electrodes 5,pixels 41 each formed so as to correspond to an area enclosed by thecorresponding scan line 21 and first signal line 22 a, first TFTs 24 athat are each a switch element arranged near the intersection betweenthe corresponding scan line 21 and first signal line 22 a andelectrically connected to these scan line 21 and second signal line 22a, second TFTs 24 b that are each a switch element arranged near theintersection between the corresponding scan line 21 and first signalline 22 b and electrically connected to these scan line 21 and secondsignal line 22 b, the first pixel electrodes 4 each electricallyconnected to the first TFT 24 a, second pixel electrodes 5 eachelectrically connected to the second TFT 24 b, and common electrodes 3each electrically connected to the common electrode driver 34.

Further, as shown in FIGS. 3A and 3B, the substrate 1 has the commonelectrode 3, the first pixel electrode 4, the second pixel electrode 5,and an insulated film 6 disposed thereon. The insulated film 6 has analignment layer 7 disposed thereon. The substrate 2 has a color filter 8and an alignment layer 7 disposed thereon. Surfaces of the substrates 1and 2 which do not face the liquid crystal each have a polarizer 11disposed thereon. Here, the order in which the electrodes and theinsulated film are arranged is not limited in order to obtain theeffects of the present invention.

The first pixel electrode 4, the common electrode 3, and the secondpixel electrode 5 disposed on the substrate 1 are linear, each have awidth of 4 μm, and are arranged substantially in parallel. The materialof these electrodes is chromium molybdenum. The second pixel electrode 5is located between the common electrode 3 and the first pixel electrode4, and the material thereof is ITO (Indium-Tin-Oxide). The distancebetween the first pixel electrode 4 and the second pixel electrode 5 is10 μm. Then, the material or width of these electrodes is notparticularly limited in order to obtain the effects of the presentinvention. However, for an increased aperture ratio, the second pixelelectrode is desirably a transparent conductor such as ITO.

In this embodiment, since all the electrodes are thus disposed on thesubstrate 1, the distribution of electric fields does not vary even ifthe substrates 1 and 2 are misaligned. Thus, the potentials provided tothe electrodes need not be adjusted for each liquid crystal displayapparatus as in the above described JP-A-9-244046 specification.

The substrates 1 and 2 are made of glass of 0.7 mm thickness. The firstTFT 24 a and the second TFT 24 b are each made of amorphous silicon 23.In the present invention, the two switch elements are thus disposed, sothat arbitrary potentials can be provided to two of the three electrodesto form an arbitrary distribution of electric fields. As a result,movements such as the twisting or rising of liquid crystals can becontrolled.

The first pixel electrode 4 and the common electrode 3 are each made ofchromium molybdenum. Insulated films 6 a, 6 b, and 6 c are each composedof silicon nitride, and have a film thickness of 0.2, 0.8, and 0.8 μm,respectively. The alignment layer 7 has a film thickness of 80 nm, andis subjected to a rubbing process for orienting a liquid crystal. Arubbing direction is inclined through 15° from the longitudinaldirection of the first pixel electrode 4.

Polymeric beads of 4 μm diameter are distributed between the substrates1 and 2 to maintain a constant gap in a liquid crystal layer. The liquidcrystal layer has a refractive-index anisotropy of 0.0947 and adielectric anisotropy of 10.5.

The polarizers 11 are arranged in a crossed Nicols manner so as toestablish the normally black mode. A transmission axis of one of thepolarizers aligns with the rubbing direction.

A back light is not restricted, and an under light type or a side lighttype may be used; a back light having color tones that provide a desiredwhite is employed in the present invention.

Active matrix driving is used in this embodiment.

The distribution of electric fields according to this embodiment will bedescribed with reference to FIG. 1. FIG. 1 corresponds to FIG. 3A, towhich equipotential lines have been added. As is apparent fromequipotential lines 13, the distribution of electric fields applied tothe liquid crystal according to this embodiment is different from thatobtained in the conventional IPS display mode as shown in FIG. 2.Further, in the IPS display mode, since only two electrodes areprovided, the distribution of electric fields cannot be arbitrarilycontrolled. According to the present invention, however, since the twoelectrodes and the two switch elements are provided, the distribution ofelectric fields can be controlled.

The distribution of electric fields can be controlled by adjusting theratio of the potentials provided to the common electrode 3, the firstpixel electrode 4, and the second pixel electrode 5. Distributions ofelectric fields obtained by adjusting the ratio of the potentialsprovided to the common electrode 3, the first pixel electrode 4, and thesecond pixel electrode 5 will be described with reference to FIG. 5.FIG. 5A shows a distribution of electric fields obtained when potentialsare provided to the common electrode 3, the first pixel electrode 4, andthe second pixel electrode 5 at a ratio of 0.0:1.0:0.5. Likewise, FIG.5B shows a distribution of electric fields obtained when potentials areprovided to the common electrode 3, the first pixel electrode 4, and thesecond pixel electrode 5 at a ratio of 0.0:1.0:0.3. In this case, therate of vertical field components is higher in FIG. 5B than in FIG. 5A.That is, in FIG. 5B, the liquid crystals rise more sharply than in FIG.5A, thus emphasizing the blue. The distribution of electric fields canbe adjusted in this manner.

As described above, in this embodiment, the vertical and horizontalfield components are regulated by providing a potential to the secondpixel electrode 5 so as to disturb electric fields formed by the firstpixel electrode 4 and the common electrode 3.

The ratio of the potentials provided to the common electrode 3, thefirst pixel electrode 4, and the second pixel electrode 5 is determinedin the following manner: The driving voltage, that is, a potentialdifference between the common electrode 3 and the first pixel electrode4, is varied while keeping the potential provided to the second pixelelectrode 5 equal to the average of the potentials provided to thecommon electrode 3 and the first pixel electrode 4. Then, a drivingvoltage with which the image becomes most bluish is determined. At thistime, the refractive-index anisotropy of the liquid crystal and the gapin the liquid crystal layer are regulated so as to obtain a desiredwhite. Then, while varying the driving voltage, the potential providedto the second pixel electrode is adjusted by the signal control circuit36 so as to obtain the desired white. In this manner, the desired whiteis obtained in all gradations.

In this case, the distribution of electric fields depends on thesequence of the electrode layers, the shapes and sizes of theelectrodes, the thicknesses and material of the insulated films, thematerial of the liquid crystal, the gap of the liquid crystal layers,the substrates, or the like. However, by correspondingly adjusting theratio of the potentials provided to the common electrode 3, the firstpixel electrode 4, and the second pixel electrode 5, the effects of thepresent invention can be obtained. Furthermore, the effects of thepresent invention can of course be obtained even if the refractive indexof the liquid crystal layer, the gap in the liquid crystal layer, theback light, or the like is different from that of this embodiment.

In this embodiment, since all the electrodes are disposed on thesubstrate 1, the variation of the distribution of electric fields isvery small even if the substrates 1 and 2 are misaligned. Consequently,this embodiment is unlikely to be affected by misalignment.

In this embodiment, the chromaticity can be controlled by adjusting theratio of the potentials provided to the common electrode 3, the firstpixel electrode 4, and the second pixel electrode 5 so as to change themanner of raising the liquid crystal. As a result, the dependence ofcolor tones on the gradation is as shown in the chromaticity chart (CIE:Comission International de l'eclairage (1976) in FIG. 6. The symbol x inthis figure denotes the chromaticity of “white”. The amount of variationis below the detection limits of human beings; this embodiment providesa liquid crystal display apparatus in which the dependence of the colortones on the gradation is very low.

COMPARATIVE EXAMPLE

The configuration of a comparative example of the present invention willbe described with reference to FIGS. 7A, 7B and 8. FIGS. 7A and 7B areviews useful in explaining the configuration of a pixel portion, andFIG. 8 is a view useful in explaining a driving system for a liquidcrystal display apparatus. More specifically, FIG. 7B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, FIG. 7A is a sectional view taken along line A-A′ in FIG.7B, and FIG. 8 is a view useful in explaining a configuration for wiringon the substrate 1.

A liquid crystal display apparatus of this embodiment has aconfiguration described below.

As shown in FIGS. 7A and 7B, the apparatus has the substrate 1, thesubstrate 2, the liquid crystal layer 12 sandwiched between thesubstrates 1 and 2 and having a positive dielectric anisotropy, theplurality of pixels 41 forming the display section, the first pixelelectrode 4 corresponding to the pixel 41, and the common electrode 3corresponding to the pixel electrode 4.

Further, as shown in FIG. 8, the apparatus comprises the signal driver32 for supplying a potential to the pixel electrodes 4, the commonelectrode driver 34 for supplying a potential to the common electrodes3, the scan driver 31 for selecting pixels, and the display controller37 for controlling the signal drivers 32, the common electrode driver34, and the scan driver 31. The substrate 1 comprises the plurality ofscan lines 21 connected to the scan driver 31, the plurality of signallines 22 connected to the signal driver 32, crossing the scan lines 21,and corresponding to the pixel electrodes 4, the pixels 41 each formedso as to correspond to the area enclosed by the corresponding scan line21 and signal line 22, the TFTs 24 that are each a switch elementarranged near the intersection between the corresponding scan line 21and signal line 22 and electrically connected to these scan line 21 andsignal line 22, the pixel electrodes 4 each electrically connected tothe TFT 24, and the common electrodes 3 each electrically connected tothe common electrode driver 34.

Further, as shown in FIGS. 7A and 7B, the substrate 1 has the commonelectrode 3 and the pixel electrode 4 disposed thereon. The insulatedfilm 6 has the alignment layer 7 disposed thereon. The substrate 2 hasthe color filter 8 and the alignment layer 7 disposed thereon. Thesurfaces of the substrates 1 and 2 which do not face the liquid crystaleach have the polarizer 11 disposed thereon.

The pixel electrode 4 and the common electrode 3, both disposed on thesubstrate 1, are linear, each have a width of 4 μm, and are arrangedsubstantially in parallel. The distance between the pixel electrode 4and the common electrode 3 is 10 μm.

The substrates 1 and 2 are made of glass of 0.7 mm thickness. The TFT 24is made of the amorphous silicon 23. The pixel electrode 4 and thecommon electrode 3 are each made of chromium molybdenum. The insulatedfilms 6 a and 6 b are each composed of silicon nitride, and have a filmthickness of 0.2 and 0.8 μm, respectively. The alignment layer 7 has afilm thickness of 80 nm, and is subjected to a rubbing process fororienting the liquid crystal. The rubbing direction is inclined through15° from the longitudinal direction of the first pixel electrode 4.

The polymeric beads of 4 μm diameter are distributed between thesubstrates 1 and 2 to maintain a constant gap in a liquid crystal layer.The liquid crystal layer has a refractive-index anisotropy of 0.0947 anda dielectric anisotropy of 10.5.

The polarizers 11 are arranged in a crossed Nicols manner so as toestablish the normally black mode. The transmission axis of one of thepolarizers aligns with the rubbing direction.

The backlight is the same as in Embodiment 1.

The active matrix driving is used in this example.

With respect to the sectional configuration of the pixel portion in thiscomparative example, a comparison between FIGS. 7A and 3A indicates thatthe configuration on the substrate 2 in this comparative example is thesame as in Embodiment 1 and that the configuration on the substrate 1therein is also the same as in Embodiment 1 except that the substrate 1does not have the second pixel electrode 5 nor the insulated film 6 cdisposed thereon.

Accordingly, in this comparative example, the lack of the second pixelelectrode 5 prevents the distribution of electric fields from beingadjusted. Further, the chromaticity varies depending on the drivingvoltage as shown in FIG. 9, and the amount of the variation is beyondthe detection limits of human beings. FIG. 9 shows the chromaticitychart (CIE Comission International de l'eclairage (1976). The symbol xin this figure denotes the chromaticity of “white”.

[Embodiment 2]

Embodiment 2 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 1 except that the common electrode 3, the first pixelelectrode 4, and the second pixel electrode 5 are made of ITO, atransparent conductive material.

In Embodiment 2, the ratio of the potentials provided to the commonelectrode 3, the first pixel electrode 4, and the second pixel electrode5 is different from that in Embodiment 1. This is because the areathrough which light is transmitted changes to vary the average ofE_(Z)/E_(X) in the area through which light is transmitted. This will bedescribed with reference to FIG. 1. As is apparent from theequipotential lines 13 in FIG. 1, the area on the common electrode 3 andthe first pixel electrode 4 has a larger E_(Z)/E_(X) than the areabetween the common electrode 3 and the first pixel electrode 4. Thus, ifthe common electrode 3 and the first pixel electrode 4 are opaque, lightis transmitted through only areas having a small E_(Z)/E_(X). On theother hand, if the above three electrodes are transparent, light istransmitted through both areas having a small E_(Z)/E_(X) and thosehaving a large E_(Z)/E_(X). As a result, the use of transparentelectrodes increases the average E_(Z)/E_(X) of the areas through whichlight is transmitted, that is, the effective E_(Z)/E_(X) thereof,compared to the use of opaque electrodes.

Thus, the ratio of the potentials provided to the common electrode 3,the first pixel electrode 4, and the second pixel electrode 5 differsfrom that in Embodiment 1, but the variation in the color tone dependingon the driving voltage can be restrained as in Embodiment 1 by adjustingthe ratio of the potentials in the same manner as in Embodiment 1.

[Embodiment 3]

Embodiment 3 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 1 except that the second pixel electrode 5 overlaps thecommon electrode 3 and is made of chromium molybdenum like the commonelectrode 3 and the first pixel electrode 4, as shown in FIG. 10.

In this embodiment, even if the second pixel electrode 5 is nottransparent, the aperture ratio does not decrease. Accordingly, thematerial of the electrodes can be selected more flexibly.

Similar effects are also obtained if the second pixel electrode 5overlaps the first pixel electrode 4.

[Embodiment 4]

Embodiment 4 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 3 except that the second pixel electrode 5 is as wide as ornarrower than the common electrode 3, overlapped thereby, as shown inFIG. 11.

According to this embodiment, compared to Embodiment 3, the apertureratio is restrained from decreasing even if the misalignment of a maskduring a manufacturing process causes the second pixel electrode 5 andthe common electrode 3 to be offset from each other.

[Embodiment 5]

Embodiment 5 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 3 except that the second pixel electrode 5 is wider than thecommon electrode 3, overlapped thereby and that the second pixelelectrode 5 is composed of ITO, as shown in FIG. 12.

According to this embodiment, compared to Embodiment 3, vertical fieldcomponents are obtained more easily, thus widening a range over whichthe color tones can be adjusted.

[Embodiment 6]

The configuration of Embodiment 6 of the present invention will bedescribed with reference to FIGS. 13A and 13B. FIG. 13B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 13A is a sectional view taken along line A-A′ inFIG. 13B.

Embodiment 6 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 1 except for the pixel configuration on the substrate 1, asshown in FIGS. 13A and 13B.

As shown in FIG. 13B, the plurality of first pixel electrodes 4 areconnected together via a first junction, the plurality of second pixelelectrodes 5 are connected together via a second junction, the pluralityof first pixel electrodes 4 and the first junction do not overlap theplurality of second pixel electrodes 5 and the second junction.

As shown in FIG. 13A, the first pixel electrodes 4 and the second pixelelectrodes 5 can be arranged in the same layer.

Furthermore, the first pixel electrodes 4, the second pixel electrodes5, the first signal line 22 a, and the second signal line 22 b arearranged in the same layer, and the common electrodes 3 and a scanningline 21 are arranged in the same layer.

According to this embodiment, compared to Embodiment 1, the number ofinsulated layers and thus the number of photolithography steps in themanufacturing process can be reduced.

[Embodiment 7]

The configuration of Embodiment 7 of the present invention will bedescribed with reference to FIGS. 14A and 14B. FIG. 14B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 14A is a sectional view taken along line A-A′ inFIG. 14B.

Embodiment 7 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 1 except that the second pixel electrode 5 is arranged belowthe first pixel electrode 4 and the common electrode 3 via the insulatedfilm 6 c and that the second pixel electrode 5 overlaps the commonelectrode 3 and the first pixel electrode 4, as shown in FIGS. 14A and14B.

According to this embodiment, as compared with Embodiment 1, thevariation of the distribution of electric fields is small even if themask is misaligned during the manufacturing process. Consequently, thisembodiment is unlikely to be affected by the misalignment of the mask.

It should be appreciated that the present invention is applicable to thecase where the common electrode 3, the first pixel electrode 4, and thesecond pixel electrode 5 are all formed of a transparent conductivematerial such as ITO.

[Embodiment 8]

The configuration of Embodiment 8 of the present invention will bedescribed with reference to FIGS. 15A and 15B. FIG. 15B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 15A is a sectional view taken along line A-A′ inFIG. 15B.

In Embodiment 8 of the liquid crystal display apparatus according to thepresent invention, the common electrode 3 is located between the firstpixel electrode 4 and the second pixel electrode 5 as shown in FIGS. 15Aand 15B and is composed of ITO. The first pixel electrode 4 and thesecond pixel electrode 5 are composed of chromium molybdenum. Thisliquid crystal display apparatus is the same as that of Embodiment 1 inthe other points.

The distribution of electric fields can be controlled by adjusting theratio of the potentials provided to the common electrode 3, the firstpixel electrode 4, and the second pixel electrode 5. Distributions ofelectric fields obtained by adjusting the ratio of the potentialsprovided to the common electrode 3, the first pixel electrode 4, and thesecond pixel electrode 5 will be described with reference to FIGS. 16Aand 16B. FIG. 16A shows a distribution of electric fields obtained whenpotentials are provided to the common electrode 3, the first pixelelectrode 4, and the second pixel electrode 5 at a ratio of 0.0:1.0:1.0.Likewise, FIG. 16B shows a distribution of electric fields obtained whenpotentials are provided to the common electrode 3, the first pixelelectrode 4, and the second pixel electrode 5 at a ratio of 0.0:1.0:0.6.In this case, the rate of vertical field components is higher in FIG.16B than in FIG. 16A. That is, the distribution of electric fields canbe adjusted.

As described above, in this embodiment, the vertical and horizontalfield components are regulated by providing different potentials to thefirst and second pixel electrodes 4 and 5 so as to disrupt the symmetryof the distribution of electric fields with respect to a centerline ofthe common electrode 3 in the longitudinal direction.

In this embodiment, the ratio of the potentials provided to the commonelectrode 3, the first pixel electrode 4, and the second pixel electrode5 is determined in the following manner: The driving voltage is variedwhile keeping the potential at the second pixel electrode 5 equal to thepotential at the first pixel electrode 4. Then, a driving voltage withwhich the image becomes most bluish is determined. At this time, therefractive-index anisotropy of the liquid crystal and the gap in theliquid crystal layer are regulated so as to obtain a desired white.Then, while varying the driving voltage, the potential provided to thesecond pixel electrode 5 is adjusted by the signal control circuit 36 soas to obtain the desired white. At this time, different potentials areprovided to the first and second pixel electrodes 4 and 5 to adjust theratio of the vertical field components to the horizontal fieldcomponents. In this manner, the dependence of the chromaticity on thegradation can be restrained.

[Embodiment 9]

The configuration of Embodiment 9 of the present invention will bedescribed with reference to FIGS. 17A and 17B. FIG. 17B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 17A is a sectional view taken along line A-A′ inFIG. 17B.

Embodiment 9 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 1 except for the pixel configuration on the substrate 1, asshown in FIGS. 17A and 17B.

As shown in FIG. 17B, plural pieces of the first pixel electrode 4 areconnected together via a first junction, plural pieces of the secondpixel electrode 5 are connected together via a second junction, theplural pieces of the first pixel electrode 4 and the first junction donot overlap the plural pieces of the second pixel electrodes 5 and thesecond junction.

Thus, as shown in FIG. 17A, the first pixel electrode 4 and the secondpixel electrode 5 can be arranged in the same layer.

Furthermore, the first pixel electrode 4, the second pixel electrode 5,the first signal line 22 a, and the second signal line 22 b are arrangedin the same layer, and the common electrode 3 and the scanning line 21are arranged in the same layer.

According to this embodiment, compared to Embodiment 8, the number ofinsulated layers and thus the number of photolithography steps in themanufacturing process can be reduced.

[Embodiment 10]

The configuration of Embodiment 10 of the present invention will bedescribed with reference to FIGS. 18A and 18B. FIG. 18B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 18A is a sectional view taken along line A-A′ inFIG. 18B.

Embodiment 10 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 8 except that the common electrode 3 is arranged below thefirst pixel electrode 4 and the second pixel electrode 5 via theinsulated film 6 c and that the common electrode 3 overlaps the commonelectrode 3 and the second pixel electrode 5, as shown in FIGS. 18A and18B.

According to this embodiment, compared to Embodiment 8, the variation ofthe distribution of electric fields is small even if the mask ismisaligned during the manufacturing process. Consequently, thisembodiment is unlikely to be affected by the misalignment of the mask.

Further, since the common electrode 3 is arranged below the first andsecond pixel electrodes 4 and 5, if TFTs of a bottom gate structure areto be produced, the common electrode 3 and the scan line 21 can beformed in the same layer. Consequently, the configuration on thesubstrate 1 can be produced more easily than in Embodiment 7.

It should be appreciated that the present invention is applicable to thecase where the common electrode 3, the first pixel electrode 4, and thesecond pixel electrode 5 are all formed of a transparent conductivematerial such as ITO.

[Embodiment 11]

The configuration of Embodiment 11 of the present invention will bedescribed with reference to FIGS. 19A and 19B. FIG. 19B is a bird's eyeview useful in explaining the configuration of the pixel 41 on thesubstrate 1, and FIG. 19A is a sectional view taken along line A-A′ inFIG. 19B.

Embodiment 11 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 10 except for the pixel configuration on the substrate 1, asshown in FIGS. 19A and 19B.

As shown in FIG. 19B, the plural pieces of the first pixel electrode 4are connected together via a first junction, the plural pieces of thesecond pixel electrode 5 are connected together via a second junction,the plural pieces of the first pixel electrode 4 and the first junctiondo not overlap the plural pieces of the second pixel electrode 5 and thesecond junction.

Thus, as shown in FIG. 19A, the first pixel electrode 4 and the secondpixel electrode 5 can be arranged in the same layer.

Furthermore, the first pixel electrode 4, the second pixel electrode 5,the first signal line 22 a, and the second signal line 22 b are arrangedin the same layer, and the common electrode 3 and the scanning line 21are arranged in the same layer.

According to this embodiment, compared to Embodiment 10, the number ofinsulated layers and thus the number of photolithography steps in themanufacturing process can be reduced.

[Embodiment 12]

Embodiment 12 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 7 except that the common electrode 3 is disposed on thesubstrate 2 and overlaps the first and second pixel electrodes 4 and 5.

As in this embodiment, even if the electrodes are located on both thesubstrates 1 and 2, the distribution of electric fields applied to theis liquid crystal is prevented from varying by arranging the electrodeson the substrate 2 so as to overlap all the corresponding electrodes onthe substrate 1, even if the substrates 1 and 2 are misaligned. Thus, adesired white can be obtained without the need to adjust the potentialsprovided to the electrodes for each liquid crystal display apparatus.

In this embodiment, the ratio of the potentials provided to theelectrodes is adjusted in the following manner: A potential difference(x₁−x₂) between the first pixel electrode 4 and the second pixelelectrode 5 is increased while maintaining the ratio of the potentialsat the common electrode 3, the first pixel electrode 4, and the secondpixel electrode 5 at (x₁+x₂)/2: x₁:x₂, where x₁ denotes the potential ofthe first pixel element 4, and x₂ denotes the potential of the secondpixel element 5. Then, a potential difference between the first pixelelectrode 4 and the second pixel electrode 5 with which the imagebecomes most bluish is determined. At this time, the refractive-indexanisotropy of the liquid crystal and the gap in the liquid crystal layerare regulated so as to obtain the desired white. Then, while varying thepotential difference between the first pixel electrode 4 and the secondpixel electrode 5, the potential ratio between the common electrode 3and the first pixel electrode 4 and the second pixel electrode 5 isadjusted by the signal control circuit 36 so as to obtain the desiredwhite. For example, the vertical field components increase when thepotential ratio is at x₁:x₁:x₂. In this manner, the dependence of thecolor tones on the gradation can be restrained.

[Embodiment 13]

Embodiment 13 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 12 except that a dielectric 9 of 2 μm thickness is arrangedon the second pixel electrode 5 as shown in FIG. 21.

According to this embodiment, compared to Embodiment 12, the horizontalfield components in the liquid crystal layer increase as shown by theequipotential lines 13, thereby improving the transmissivity.

Further, the present invention provides the same effect even if thedielectric 9 is a color filter or a flattened film.

[Embodiment 14]

Embodiment 14 of the liquid crystal display apparatus according to thepresent invention is the same as the liquid crystal display apparatus ofEmbodiment 13 except that a recess 9′ penetrating the dielectric 9 isformed in a portion of the dielectric 9 which overlaps the second pixelelectrode 5 as shown in FIG. 22.

In the dielectric 9, an electrode is considered to be present only inthe recess 9′, so that by processing the recess into an arbitrary shape,a distribution of electric fields similar to the one obtained if anelectrode of an arbitrary shape is produced.

In this embodiment, the recess 9′ is formed in the dielectric 9 near thecenter of the pixel. This is equivalent to the arrangement of the commonelectrode 3 only in the neighborhood of the center of the pixel; theliquid crystal rises toward the location of this recess. Consequently,the liquid crystal rises in all directions to improve the angle ofvisibility characteristic.

The manner of providing the potentials to the electrodes will bedescribed below in brief.

In the conventional IPS display mode, the color tones monotonouslybecome yellowish as the driving voltage increases. Thus, the liquidcrystal need not be raised when the driving voltage is highest.Consequently, with the liquid crystal display apparatus configured as inEmbodiment 1, when the driving voltage is lowest, the potential providedto the second pixel electrode 5 may be set equal to the average of thepotentials provided to the first pixel electrode 4 and the commonelectrode 3 so that a distribution of electric fields similar to thatobtained in the conventional IPS display mode can be obtained. On thecontrary, if the color tones monotonously become bluish as the drivingvoltage increases, the potential provided to the second pixel electrode5 may be set equal to the average of the potentials provided to thefirst pixel electrode 4 and the common electrode 3 when the drivingvoltage is highest.

Also with the liquid crystal display apparatus configured as describedin Embodiment 2 or 7, a distribution of electric fields similar to thatobtained in the conventional IPS display mode is obtained when thepotential provided to the second pixel electrode 5 is the average of thepotentials provided to the first pixel electrode 4 and the commonelectrode 3. Accordingly, similarly, the potential provided to thesecond pixel electrode 5 may be set equal to the average of thepotentials provided to the first pixel electrode 4 and the commonelectrode 3 when the driving voltage is highest or lowest.

Likewise, with the liquid crystal display apparatus configured asdescribed in any of Embodiments 3 to 5, when the driving voltage ishighest or lowest, the potential provided to the second pixel electrode5 may be set substantially equal to the potential provided to any one ofthe first pixel electrode 4 or the common electrode 3, which isoverlapped by the second pixel electrode 5, so that a distribution ofelectric fields similar to that obtained in the conventional IPS displaymode can be obtained.

Similarly, with the liquid crystal display apparatus configured asdescribed in Embodiment 8 or 11, when the driving voltage is highest orlowest, the potential provided to the second pixel electrode 5 may beset equal to the potential provided to the first pixel electrode so thata distribution of electric fields similar to that obtained in theconventional IPS display mode can be obtained.

Likewise, with the liquid crystal display apparatus configured asdescribed in any of Embodiments 12 to 14, when the difference betweenthe potentials provided to the first pixel element 4 and to the secondpixel element 5 is largest or smallest, the potential provided to thecommon electrode 3 may be set substantially equal to the average of thepotentials provided to the first and second pixel electrodes 4 and 5 sothat a distribution of electric fields similar to that obtained in theconventional IPS display mode can be obtained.

According to the present invention, the common electrode, the firstpixel electrode, and the second pixel electrode can adjust thedistribution of electric fields applied to the liquid crystal, thusproviding a liquid crystal display apparatus which can adjust the colortones and which can restrain the variation in the color tones dependingon the driving voltage.

1. A liquid crystal display apparatus, comprising: a first substrate; asecond substrate arranged opposite the first substrate; a liquid crystallayer sandwiched between said first substrate and said second substrate;and a plurality of pixels which are sandwiched between said firstsubstrate and said second substrate and form a display section, whereineach of said pixels is provided with a first pixel electrode and asecond pixel electrode both corresponding to said pixel, and a commonelectrode corresponding to said first and second pixel electrodes. 2.The liquid crystal display apparatus according to claim 1, wherein saidfirst pixel electrode, said common electrode, and said second pixelelectrode are disposed on said first substrate.
 3. The liquid crystaldisplay apparatus according to claim 2, wherein in each pixel, saidfirst pixel electrode and said common electrode are linear and arearranged substantially in parallel, and at least part of said secondpixel electrode overlaps said first pixel electrode or said commonelectrode.
 4. The liquid crystal display apparatus according to claim 3,wherein said second pixel electrode is linear, and said second pixelelectrode is as wide as or narrower than the first pixel electrode orcommon electrode, which is overlapped by the part of the second pixelelectrodes.
 5. The liquid crystal display apparatus according to claim3, wherein said second pixel electrode is linear, and said second pixelelectrode is wider than said first pixel electrodes or common electrode,which is overlapped by the part of the second pixel electrode.
 6. Theliquid crystal display apparatus according to claim 2, wherein saidfirst pixel electrode and said common electrode are linear and arearranged substantially in parallel, and said second pixel electrode islocated below said first pixel electrode and said common electrode, saidsecond pixel electrode overlaps said first pixel electrode and saidcommon electrode, and insulated films are disposed between said secondpixel electrode and said first pixel electrode and between said secondpixel electrode and said common electrode.
 7. The liquid crystal displayapparatus according to claim 2, wherein said first pixel electrode andsaid second pixel electrode are linear and are arranged substantially inparallel, and said common electrode is located between said first pixelelectrode and said second pixel electrode.
 8. The liquid crystal displayapparatus according to claim 2, wherein said first and said second pixelelectrodes are linear and are arranged substantially in parallel, and atleast part of said common electrode overlaps said first or said secondpixel electrode.
 9. The liquid crystal display apparatus according toclaim 2, wherein said first and said second pixel electrodes are linearand are arranged substantially in parallel, and said common electrode islocated below said first and second pixel electrodes, said commonelectrode overlaps said first and said second pixel electrodes, andinsulated films are disposed between said common electrode and saidfirst pixel electrode and between said common electrode and said secondpixel electrode.
 10. The liquid crystal display apparatus according toclaim 1, wherein said first and said second pixel electrodes aredisposed on said first substrate, and said common electrode is disposedon one of said first substrate and said second substrate.
 11. The liquidcrystal display apparatus according to claim 3, wherein when thedifference between the potentials provided to said first pixel electrodeand to said common electrode is largest or smallest, the potentialprovided to said second pixel electrode is substantially equal to thepotential provided to said first pixel electrode or common electrode,which is overlapped by said second pixel electrode.
 12. The liquidcrystal display apparatus according to claim 7, wherein when thedifference between the potentials provided to said first pixel electrodeand to said common electrode is largest or smallest, the potentialprovided to said second pixel electrode is substantially equal to thepotential provided to said first pixel electrode.